Japanese Patent Application Publication No. 2003-247259 discloses a toilet apparatus provided with a private part washing device for cleaning a specific portion, which comprises, in addition to a cleaning nozzle that sprays water for cleaning the local part, a detergent nozzle which sprays a detergent solution for cleaning the actual cleaning nozzle, and a bowl cleaning nozzle which sprays the detergent solution onto the inner surface of the bowl in order to clean the inner surface of the bowl. These nozzles are connected to a common water supply channel which is connected to a water source and are operated selectively according to requirements. This water supply channel is composed in such a manner that water from the water source is supplied to the cleaning nozzle, a cleaning tank containing detergent is connected to an intermediate point of the water supply channel, and when the detergent nozzle or bowl cleaning nozzle is operated, detergent is expelled into the supply channel and mixed with the water to create a detergent solution. This water supply channel is formed independently from a main water supply channel for supplying cleaning water for expelling dirt from the bowl, and carries a small amount of water in comparison with the main water supply channel. Furthermore, the amount of detergent used is also small and therefore it is possible to make the detergent tank small in size, in such a manner that it does not detract from the external appearance of the toilet apparatus, wherever it may be disposed inside or outside the toilet apparatus.